Nylon (i.e., polyamide) oriented monofilament has increasingly found acceptance as a preferred material for commercial fishlines, as discussed in U.S. Pat. Nos 4,459,337 (Hansen) and 4,584,240 (Herbert and Rackley) and the art referred to therein.
Lost, entangled, and abandoned fishlines are becoming major marine contaminants in the world's oceans, lakes and streams. As synthetic polymers have become the material of choice for such lines (due to their combination of strength and flexibility as well as their retention of these properties in use), more of these materials have accumulated, especially in heavily-fished waters. Snags and tangles of broken fishline products, including nets, are a growing hazard for entrapping fish, ducks and other wildlife. Many attempts have been made to overcome this problem without a satisfactory solution, hitherto.
We have analyzed past attempts, and have noted that many have attempted to develop degradable fishlines by increasing the hydrolysis rate of the polymers used to make the lines. In our opinion, however, this approach has failed because success in making and using a polymer that hydrolyzes more rapidly tends to shorten the total useful lifetime of the line; hydrolysis tends to occur not only while the line is submerged in water but also continues on wet line stored on a reel or when moisture is absorbed from humid air.
The desirability of a fishline, especially for casting, baitfishing, trolling, jigging, etc., depends greatly on the balance of strength, bending flexibility and longitudinal stiffness. This is discussed to some extent in U.S. Pat. No. 4,584,240. Deterioration in properties, e.g., by hydrolysis, affects not only the strength of a line, but also the balance of properties.